Stinging plant (6)
I believe the answer is:
nettle
'stinging plant' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for nettle that I've seen before include "Annoy; common weed" , "Stinging weed - pester" , "Common stinging plant" , "Sting or annoy with the plant" , "Wild plant - annoy" .)